A modified acoustic-turbulent scattering model for long-range propagation with wind tunnel validation

Abstract

We present a newly developed ‘bridging’ model to quantify turbulent effects on long-range acoustic propagation in the atmosphere. The bridging model is incorporated into an existing validated Burgers’ equation solver. The new model combines the scattering model of Ostashev and Wilson and a traditional refraction model for acoustic-turbulent interaction. A new attenuation coefficient is obtained that is consistent with the atmospheric attenuation coefficient via integration of energy loss over all scattering angles. To validate and quantify the effect of the new model, we conduct a series of propagation experiments in the National Science Foundation funded University of Florida Boundary Layer Wind Tunnel. A synthetic noise signal propagates through the tunnel, which has controllable boundary layer turbulent statistics via fan speeds and hundreds of individually controlled roughness elements. We compare predictions of the bridging model, Ostashev and Wilson’s model, and the experiments of the wind tunnel. Also, we perform example long-range predictions using the new model and Ostashev and Wilson’s model with a synthetic tornadic infrasound signal. A sensitivity test of model parameters is performed. We show that for particular atmospheric conditions and turbulent statistics, the bridging model has particular advantages with minimal additional computational expense.